Location: French Gulch, CA
Field Office: Redding Field Office
The Scorpion Mine adit is near the rural community of French Gulch in Shasta County, California. It is in the French Gulch-Deadwood gold mining district which was first prospected in the 1850's for placer and lode deposits. Lode mining continues intermittently in present day.
Deposit types are narrow high angle, low sulfide and Au-quartz veins, which were developed via underground shafts, adits, tunnels and stopes.
The project "Scorpion Adit" occurs on an 80-foot wide strip of public land remaining between two patented mining claims: Scorpion Gold MC(MS-2454) and the Empire MC (MS2733). The California Water Quality Control Board has identified the Scorpion Adit as discharging arsenic laden waters at concentrations of 300 ug/l over State water quality objectives, thus adversely impacting downstream waterways. Nickel and Zinc concentrations (25, 130 ug/l) also exceed effluent limits.
The Scorpion adit portal is totally collapsed and the drainage flows from the base of the collapsed debris. Based on orientation of the vein structure, the major source of the metal-bearing waters probably comes from underground mine workings on the adjoining private lands. This proposal is to prepare an Environmental Assessment, do a Potentially Responsible Party search, obtain private land access rights to improve and use the access road, excavate and stabilize the collapsed portal, evaluate the conditions of the adit, determine sources of water contamination, and then construct a valve concrete bulkhead to seal and contain the mine effluent.